bp.johs.] BUFFALO FORK REGION. 463 



21. Gray-buff sandstone, in places thin-bedded, imperfectly exposed, 

 probably a heavy bed, elevation about 1,000 feet above the river. 



22. Hiuli bench, strewn with water-worn gravel and bowlders of all 

 sorts of rock, elevation 1,200 to 1,300 feet. 



23. Heavy-bedded buff sandstone, 25 feet exposed ; dip, 10° to 15°, 

 northeastward. Elevation about 1,500 feet. 



24. Slope, covered with drift materials. 



25. Brown and buff shaly sandstone, elevation 1,660 feet. 



26. Brownish drab clay and drift-covered slope. 



27. Heavy conglomerate deposit crowning the divide, and eroded into 

 knobs. This deposit is made up almost entirely of thoroughly water- 

 worn lobbies and small bowlders of white to red quartz and quartzose 

 rock, gneiss and granite being sparsely represented. A brownish, indu- 

 rated, arenaceous material forms the paste or cementing medium hold- 

 ing the cobble-stones, which latter are weathered out in immense quan- 

 tities in the slopes. 



There can be no question as to the epochal identity of the sandstones 

 and ashy or drab clays shown in the above section with the deposits 

 occurring in the upland south of Buffalo Fork. But no clew as to the 

 age of the heavy mass of water- worn bowlders and pebbles crowning 

 the heights in the vicinity of Station XL VIII was obtained. The lat- 

 ter deposits, it seems, prevail over a considerable area of this high water- 

 divide, extending over to the region about the sources of the Snake, a 

 few miles to the north, where Professor Bradley mentions their occur- 

 rence hi the following terms : "Ascending the high, sharp ridge on the 

 west side of this valley [the Snake rises in a "hat valley-divide"], at 

 least 500 feet high, we find its slopes to consist entirely of large and 

 small well-rounded pebbles of variously-colored quartzites up to the very 

 summit, where this deposit is just pierced by an outcrop of the gray 

 trachytic lavas and red basalt, partly vesicular, though mostly compact, 

 which form the nucleus of the ridge. We here stood upon one of the 

 highest points in that neighborhood, about 8,654 feet [9,609 feet, subse- 

 quent determination recorded on Professor Bradley's geological mapj 

 above the sea ; so that we were entirely at a loss as to the source from 

 which had flowed the large river which had distributed such immense 

 amounts of gravel and sand. The deposit is evidently very ancient, but 

 no considerable consolidation had taken place." * * * " Passing 

 westward the quartzite-gravel continues for several miles, though the 

 mass of all the ridges is composed of a coarse volcanic breccia." 



The inclination of the conglomerate in the vicinity of Station XL VIII 

 could not be satisfactorily determined. The crest of the ridge, which 

 extends in a north-south course about a mile, perhaps more, is eroded 

 into knobs strewn with cobble-stones, and studded with dwarf, storm- 

 rent pines, firs, and cedars. It presents in these respects a feature en- 

 tirely unique in our experience in this region, recalling late Post-Tertiary 

 accumulations found in other regions ; indeed, the loose materials are 

 physically identical with those forming the terraces and occurring in 

 the beds of all the streams flowing into Jackson's Basin from this quar- 

 ter. The west side of the ridge falls steeply into a deep valley, the 

 slopes densely wooded, and showing here and there slides, at the foot of 

 which the cobble-stones are piled in great heaps. This valley apparently 

 flows out into that to which the name Big Bend Creek was applied by 

 the Snake Biver expedition of 1872, and its sources are the same as the 

 stream to which Captain Jones, the following year, gave the name Pa- 



